In this study, the effect of non-ionizing radiation on the integrity of mature spermatocytes was examined. Semen was obtained from 10-month-old turkeys and dilluted to a concentraton of 3.5 times 10 to the 8th power sperm/ml using Beltsville Poultry Semen Extender. The sperm was exposed for 30 minutes to 2.45 GHz microwave radiation at specific absorption rates (SAR's) of 1, 10 and 50 mW/g. The waveguide exposure system maintained the control (non-irradiated) and irradiated samples at 40 plus 0.15 degrees centigrade throughout the experiment. Before and after irradiation, aliquots of the suspensions were removed and the viabilities were determined. Initially, the viability was 96% and was not affected by microwave radiation at any of the exposure levels examined. The release of the soluble enzymes, lactic acid dehydrogenase and glutamic oxalic transaminase by the sperm into the suspending media was also determined. Controls released approximately 6 and 18% for the LDH and GOT, respectively and the exposed had similar values. Thus, microwave radiation appeared to have no adverse effects on the parameters measured for mature spermatocytes irradiated in vitro. Other aspects of sperm physiology following microwave radiation are now being examined.